We propose to continue evaluation of an embryonic chick duodenal bilayer cell culture system, which responds to cortisol with morphologic evidence of accelerated differentiation. A rocket immunoassay (RoIA) for avian intestinal alkaline phosphatase has been developed to allow biochemical assessment of differentiation. After determining the biochemical response to cortisol in bilayer cultures, we will make similar observations in pure epithelial cells separated from the bilayers with collagenase. If, as in the lung, we find that fibroblasts are necessary for the epithelial response to cortisol, we will undertake conditioned medium transfer experiments to determine if soluble factors are involved. We will also continue studies of embryonic chick hepatocytes (grown in serum free medium) and hepatic fibroblasts and make similar observations to those noted above, with respect to glucocorticoid inducibility of tyrosine aminotransferase.